Question

The inner circumference of a circular track is 330m. The track is 10.5m wide everywhere. Calculate the cost of putting up a fence along the outer circle at the rate of Rs20 per metre.​

Answer 1

Question

The inner circumference of a circular track is 330m. The track is 10.5m wide everywhere. Calculate the cost of putting up a fence along the outer circle at the rate of Rs20 per metre.

Solution

Let r and R be the inner and outer radii of circular track respectively.

Inner circumference =330m

⇒2πr=330

$r = \frac{330}{2 \times \frac{22}{7} } \\ = 52.5$

Therefore,

Outer radius =r+10.5=52.5+10.5=63m

Outer circumference =2πR

$= 2 \times \frac{22}{7} \times 63 \\ = 396$

Cost of putting fencing on 1m=20rupees

Therefore,

Cost of putting fencing on 396m =20×396 =Rs.7920

the cost of putting up a fence along the outer circle at the rate of Rs20 per metre.= 7920 rupees

hope it helps ☺️

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Answer 2

Refer the attachment ↑